How to convert to black-and-white in Photoshop 7, CS, CS2 Part 2 (Channel Mixer Layer)

NOTE: This was originally posted on shutterstation.com, but since decommissioning that site I've pulled some of the articles here so they don't get lost.

In Part 1 of this series I showed you how to convert a color photograph to black-and-white using Photoshop CS3 or CS4 using a Black & White Adjustment Layer, but what if you have an older version of Photoshop? Well, there are a few options, but the one I used the most often is using the Channel Mixer, which we'll discuss today. It's also arguably the easiest way to convert to black-and-white that gives you some control over the tonal values. Here's how to do it using Photoshop CS2 as an example, but it works the same way with older versions:

• Start with the color image and add a Channel Mixer Layer. You can do it by either going to Layer>New Adjustment Layer>Channel Mixer, or by clicking in the New Adjustment Layer icon in the Layers pallete (see screenshot below).
• The Channel Mixer adjustment layer option dialog box will open up. To turn the photograph into black-and-white just ensure you tick the Monochrome checkbox at the bottom of the dialog box. From here, you can adjust the Red, Green and Blue channels independently until you get the effect you want.

Remember that you can use negative numbers as well as positive. In general, you should aim for the sum total of the Red, Green, and Blue channels to equal 100% unless you're after a specific look. Going over 100% will cause additional tone adjustments that can blow out hightlights, clog up shadows, and create muddy midtones. Give it a try for yourself, the best way to learn is to experiment.